A robust large-scale poloidal flux dynamo can help us understand the prevalence of jets across a wide range of astrophysical systems. Even though typical jet-producing accretion discs are geometrically-thick near the BH, they may be thin at large radii [1]}. Thin discs are thought to be incapable of efficiently transporting large-scale poloidal magnetic flux from the ambient medium to the BH [2]}, [3]}, [4]}, decreasing the prospects for jet formation. However,
if the outer thin disc can transport even just a very weak poloidal magnetic flux, dynamo action in the inner, geometrically-thick disc could amplify the magnetic flux in situ to levels sufficient for forming jets. In some systems the available magnetic flux appears insufficient to account for the observed jet power, such as the jetted TDE Swift J1644+57, for which the stellar magnetic flux falls several orders of magnitude short of that necessary to power the observed jet [5]}, [6]}. The rapid dynamo action we find in this work could help the newly formed TDE accretion disc to amplify the stellar flux to levels sufficient for the production of luminous jets (see also [7]}).
